JP6161794B2 - Apparatus for drying and sintering a metal-containing ink on a substrate - Google Patents

Description

  The present invention is an apparatus for drying and sintering a metal-containing ink on a substrate, a plurality of light emitters for irradiating the substrate, and for reflecting radiation to the substrate It has a reflector, and the radiator and the substrate are related to an apparatus that can move relative to each other in the transport direction.

  The apparatus for drying and sintering the metal-containing ink in the present invention is used to cure the printed film. This device is used, for example, in the production of electronic circuit elements, in particular in the production of RFID, organic solar cells, OLEDs or printed batteries.

  It is known that electronic circuit elements can be manufactured simply and at low cost by printing methods. Such electronic circuit elements are therefore also referred to as printed electronics, ie “Printed Functionalities” or “Printed Electronics”.

  During the manufacture of printed electronics, first, in a first method step, a metal-containing ink is deposited as a thin film by a printing method on a suitable substrate, for example a plastic film, paper or glass. The ink film thickness is generally between 0.3 μm and 3.0 μm. Various printing methods can be used to deposit the ink coating. In many cases, screen printing, roll-to-roll or ink jet printing is used. In the case of inkjet printing, the metal-containing ink is transferred onto the substrate in the form of droplets from an inkjet printer. In this method, each copy is newly created, so it is counted as one of the digital printing methods.

  Inks used in the manufacture of printed electronics contain high concentrations of small metal particles, and the particle size of the metal particles is often in the nanometer range. The metal particles are dispersed in an aqueous or organic dispersant. The ink can further contain organic additives, for example to improve particle crosslinkability, solubility, wettability, or to prevent agglomeration, or aqueous addition to improve ink processability Agents can also be included.

  In order to impart conductivity and durability to the coating on the substrate, it is necessary to dry and sinter the ink coating in the second method step. The first drying process contributes to the removal of volatile components of the ink, such as organic additives or dispersants. However, the metal particles in the metal particle coating remaining on the substrate are initially present as individual particles, and these individual particles are subjected to a subsequent sintering process to impart conductivity to the coating. Must be joined together. High conductivity is achieved, for example, by inks containing silver nanoparticles having a solid content of about 50%.

  A number of drying and sintering methods are used in the manufacture of printed electronics. The drying of the ink film can be performed, for example, by using a warmed gas. For example, air, nitrogen, or a rare gas is suitable as the gas. However, in the manufacture of printed electronics, basically, a base material made of a plastic with limited heat resistance is used, and therefore the temperature of the gas to be heated cannot be arbitrarily selected as a high temperature. Thus, in many cases, only the drying of the coating is performed by the use of a warmed gas. Furthermore, a large space is required to use a gas for drying the coating, and the processing time is increased.

  Therefore, a radiation source is used to irradiate the coated substrate with light radiation to still ensure a rapid drying and sintering process. In this apparatus, UV radiation sources, such as mercury vapor discharge lamps or LEDs, and radiation sources emitting NIR radiation, such as pulsed xenon flash lamps or krypton flash lamps, or NIR laser diodes are used.

  For example, US 2010/0003021 describes a single, for example in the form of a xenon flash lamp, suitable for emitting radiation having a wavelength in the visible range, infrared range, and / or UV range. An apparatus for drying and sintering metal-containing inks using a radiation source is disclosed. The apparatus further includes a control unit for controlling radiation based on the optical properties of the coating being cured.

  However, xenon flash lamps have several drawbacks. That is, xenon flash lamps regularly produce high power density radiation and are relatively expensive. Further, when the xenon flash lamp is used, the irradiation field is not uniformly irradiated. In particular, when the base material and the flash lamp relatively move at high speed, the irradiation field may be unevenly illuminated. This can affect the uniform evaporation of the volatile components of the metal-containing ink.

  Furthermore, it has been found that by using a single radiation source to simultaneously dry and sinter metal-containing inks, the sintering process can proceed incompletely. By proceeding simultaneously with the drying and sintering processes, the surface has already been sintered, while the volatile components are not completely evaporated from the film located deep in the coating. May be. If this volatile component is further heated during the joint drying and sintering process, a microscopic explosion can occur, which can damage the already sintered film. . Such explosions regularly impair the conductivity of the coating.

  In order to avoid this drawback, US 2013/0043221, in which the high-level apparatus described at the beginning is disclosed, describes a first flash having a low irradiation power in order to evaporate volatile components. It is proposed to provide a lamp and to arrange a separate second flash lamp having a relatively high radiation output for sintering the coating downstream of the first flash lamp as viewed in the direction of substrate transport .

Technical Problem The separate arrangement of the second radiation source assumes a large structural space in which the second radiation source is arranged. That is, the second radiation source impedes the compact structure of the device. Furthermore, an apparatus including a plurality of lamps is troublesome to manufacture and contributes to an increase in manufacturing cost. The flash lamp further has the disadvantages mentioned above. That is, flash lamps are expensive and are regularly designed for high illumination density.

  Therefore, an object of the present invention is to dry and sinter a metal-containing ink that can uniformly irradiate a substrate, has a compact structure, and can be manufactured easily and at low cost. It is to provide an effective device.

SUMMARY OF THE INVENTION The above object starts from an opening device for drying and sintering metal-containing inks as described in the superordinate concept mentioned at the outset, wherein said light emitter comprises a cylindrical radiator tube, a radiation An infrared radiator having a longitudinal axis of the tube, wherein the infrared radiator has a radiation component of IR-B radiation of at least 30% of the total radiator output and a radiation component of IR-C radiation is a total radiator Emits radiation that is at least 5% of the output, each infrared emitter such that the longitudinal axis of the radiator tube of the infrared emitter is parallel to each other and extends transverse to the transport direction. It is arranged in one radiator module, and a predetermined irradiation field on the surface of the substrate is divided into a drying zone and a sintering zone arranged on the downstream side of the drying zone when viewed in the transport direction. Irradiated to be divided, the dry The problem is solved by being exposed to an average irradiation density of at least 15% lower than the sintering zone along a central axis extending in the conveying direction.

  Starting from the apparatus for drying and sintering metal-containing inks described in the superordinate concept, two modifications are proposed according to the invention. One of them relates to the type of light emitter, and the other relates to the arrangement of the light emitter inside the radiator module associated with the irradiation field.

  In general terms, when drying and sintering metal-containing inks, it is better to use a light emitter that forms a narrow-band or discrete emission spectrum in the visible or IR-A range for this purpose. (Reference: Z. Radivojevic et al .: Optimised curing of silver ink jet based printed traces, Proceedings of 12th International Workshop on Thermal Investigations of ICs -Therminic 2006, Nice: France (2006) R. Cauchois et al .: Impact of variable frequency microwave and rapid thermal sintering on microstructure of inkjet-printed silver nanoparticles, J. Mat. Sci 47, (2012), p. 20; J. West et al .: Photonic Sintering of Silver Nanoparticles: Comparison of Experiment and Theory, in Volodymyr Shatokha [Ed.]: Sintering-Methods and Products.InTech: 2012; SPIE 6879 (2008)).

  In contrast, the device according to the invention comprises a plurality of infrared emitters, the emission spectrum of which are substantially comprised of a radiation component in the IR-B range and a radiation component in the IR-C range. .

  The metal-containing ink is a dispersion liquid in which solid metal particles are dispersed in a dispersant. The metal particles themselves have a high reflectivity for incident IR-B and IR-C radiation. IR-B and IR-C radiation emitted from infrared emitters and radiation diffusely reflected from metal particles are distributed within the film to be dried and are therefore mainly separated from the metal-containing ink. Can be used to irradiate the components.

  Such other components often include organic compounds that have good absorption properties for radiation having wavelengths in the above range. IR-B radiation and IR-C radiation are regularly absorbed by dispersants and volatile materials, so that the other component can evaporate. Thus, IR-B radiation and IR-C radiation contribute to good drying of the ink before the metal particles are bonded together in the sintering process. Therefore, the use of IR-B and IR-C radiation also reduces the occurrence of micro-explosions in subsequent sintering processes.

  The total radiator power is the integrated illumination power related to the radiation area of the radiator tube array, in units of W. If the infrared radiator emits radiation whose radiant component of IR-B radiation is at least 30% of the total radiator output and whose radiant component of IR-C radiation is at least 5% of the total radiator output Good results are achieved.

  In this connection, it has been found to be advantageous for the infrared radiator to emit a radiation component in the visible range and a radiation component in the IR-A range. Radiation having a wavelength in the above range has higher radiant energy compared to IR-B and IR-C radiation and is particularly suitable for sintering metal particles. IR-A radiation has a wavelength in the range of 0.78 μm to 1.4 μm, IR-B radiation has a wavelength in the range of 1.4 μm to 3.0 μm, and IR-C radiation has a wavelength of 3 μm. To 1000 μm.

  Furthermore, according to the invention, a plurality of infrared radiators are arranged in one common radiator module. Unlike a plurality of separate radiators, such a radiator module requires only one common casing for a plurality of infrared radiators and thus contributes to the compact structure of the device of the invention. .

  Furthermore, by using an infrared radiator with a cylindrical radiator tube, a plurality of infrared radiators can be compactly arranged in one common radiator module. This contributes to the fact that according to the invention each infrared radiator is arranged in one radiator module so that the longitudinal axes of the infrared radiators are parallel to each other. At the same time, by arranging the radiator tubes in parallel, a planar radiator suitable for planarly irradiating the substrate with a high irradiation density can be obtained. This also contributes to the fact that each infrared radiator is arranged such that the longitudinal axis of each infrared radiator extends transverse to the transport direction. In this connection, it has proved advantageous if the radiator longitudinal axis extends at an angle in the range of 45 ° to 90 ° with respect to the conveying direction. In the simplest case, the radiator modules are arranged such that the radiator longitudinal axis of each infrared emitter extends perpendicular to the transport direction.

  The radiator module is configured such that the field is formed by two different zones, namely a drying zone and a sintering zone. The term field is understood to be the same size orthogonal projection of the radiator module on a plane defined by the substrate.

  The drying zone and the sintering zone differ in terms of irradiation density. The irradiation density of these two zones is adapted to the process that proceeds during drying of the metal-containing ink and the process that proceeds during sintering. These two zones can further have different maximum temperatures and temperature profiles.

  The drying zone and the sintering zone are in direct contact or spaced from each other. There can be a transition zone between the drying zone and the sintering zone, the irradiation density of the transition zone being in the range between the irradiation density of the drying zone and the irradiation density of the sintering zone.

  Since the radiator module and the substrate are movable relative to each other in the transport direction, the substrate passes through both the drying zone and the sintering zone. The radiator module is configured such that the substrate first passes through the drying zone and then passes through the sintering zone.

  According to the invention, the drying zone has a lower average irradiation density than the sintering zone along the central axis extending in the conveying direction. As the irradiation density in the drying zone is low compared to the sintering zone, the energy input in the drying zone is smaller, so that no sintering process can occur during drying. The average irradiation density of the sintering zone is designed to sinter the metal particles. Since the coating has already passed through the drying zone, an effective sintering process is possible in the sintering zone.

  The irradiation density of the drying zone and the irradiation density of the sintering zone are different, for example, by properly selecting the spacing between adjacent radiators and by using different radiator types. This can be achieved by operating the radiator with parameters (eg, operating current, operating voltage).

  Since the drying zone and the sintering zone are formed by one common radiator module, the two zones have a relatively small distance from each other. This reduces the cooling process that can occur while the substrate is transported from the drying zone to the sintering zone. Thus, the radiator module contributes to the high energy efficiency of the device of the present invention.

  In an advantageous embodiment of the device according to the invention, a plurality of said infrared emitters is a first type of infrared emitter having a radiation maximum in the wavelength range between 1600 nm and 3000 nm, and a wavelength between 900 nm and 1600 nm. A second type of infrared emitter having an emission maximum in the range.

  Infrared radiators with different emission maxima regularly cause different energy inputs to the substrate. Thus, using a plurality of different infrared emitters can contribute to forming a single field having a plurality of different zones, such as a drying zone and a sintering zone. The first type of infrared emitter emits a radiation component that is absorbed by the volatile components of the metal-containing ink in particular. Accordingly, the first type of infrared radiator is suitable for irradiation in the drying zone. The second type of infrared emitter exhibits an emission maximum between 900 nm and 1600 nm, thus regularly causing a relatively high energy input to the substrate. The radiation emitted by the second type of infrared emitter is also absorbed by the metal particles. Therefore, the second type of infrared radiator is suitable for facilitating the sintering process. A second type of infrared radiator is preferably provided for irradiation of the sintering zone.

  In a further advantageous embodiment of the device according to the invention, a plurality of said first type infrared emitters and a plurality of said second type infrared emitters are provided, said first type infrared rays being adjacent to each other. The distance between the radiators is larger than the distance between the second type infrared radiators adjacent to each other.

  The distance between adjacent infrared radiators affects the irradiation density of the irradiation field. If the interval is increased, the irradiation density is decreased. On the other hand, if the interval is decreased, the irradiation density is increased. Preferably, the first type of infrared radiator is assigned to the drying zone of the field and the second type of infrared radiator is assigned to the sintering zone of the field. Since the distance between the first type infrared radiators is larger than the distance between the adjacent second type infrared radiators, the first type infrared radiators form a lower illumination density. According to the invention, this is particularly advantageous in the drying zone.

  It has been found that it is advantageous for the infrared radiator to emit the radiation continuously.

  In particular, in the case of a radiator that operates intermittently, for example a flash lamp, the irradiation density varies due to the relative movement of the substrate and the radiation source in an apparatus for drying and sintering the ink. Arise. Therefore, an infrared emitter that emits radiation continuously is particularly suitable for uniformly irradiating the substrate. A radiator module including such an infrared radiator forms a constant irradiation field in time.

  In a preferred embodiment of the device according to the invention, the infrared emitter has a broadband emission spectrum, the broadband emission spectrum being at least 10% of the total radiator output combined in the visible and IR-A ranges. It has the radiation component.

  A radiator having a broad emission spectrum can be used for drying and sintering metal-containing inks. In particular, radiation having a wavelength in the visible range and IR-A radiation have a higher radiant energy compared to IR-B radiation and IR-C radiation, and are particularly suitable for sintering metal particles. However, the sintering efficiency in this case depends on the irradiation density. When using a radiator with a radiant component of IR-A radiation of less than 30%, each irradiation density in the drying and sintering zones can be adjusted by appropriately matching the spacing between adjacent radiators. .

In a further preferred modification of the device of the present invention, the radiation field, the range of 800 cm ² of 6000 cm ^2, particularly preferably has a total area ranging from 1500 cm ² of 2000 cm ^2, the sintering and the area of the drying zone Each zone area is at least 30% of the total area, and preferably the dry zone area is between 35% and 65% of the total area.

The area of the irradiation field affects the drying period and the sintering period per unit area of the substrate. When the area of the irradiation field is smaller than 800 cm ^{2, the} substrate area to be dried per unit time is relatively small, and thus the drying cost is increased. A device having an irradiation field with a total area greater than 6000 cm ² and at the same time good irradiation density can only be produced at high cost.

  Furthermore, it is basically desirable that the areas of the drying and sintering zones occupy as much of the total area as possible. Thus, it has been found advantageous for an effective drying process that the drying and sintering zones are at least 30% of the total area. Since the substrate and the radiator module are movable relative to each other, the effective irradiation period of the substrate depends on the area of the drying or sintering zone. If the area of the zone is large, the time required for irradiation of the substrate becomes longer. The irradiation period can be adapted to ensure an effective drying and sintering process. This can be done by appropriate selection of the areas of the drying and sintering zones. If the drying / sintering zone has an area in the range between 35% and 65% of the total area, the ratio of the irradiation period of the drying zone to the irradiation period of the sintering zone is 1: 2 and 2: A range between 1 can be accommodated.

  It has proved advantageous if the drying zone and the sintering zone have the same area.

  If the drying zone and the sintering zone have the same area, effective irradiation of the substrate in these two zones can be ensured over an equivalent period.

The drying zone preferably has an average irradiation density of less than 50 kW / m ² along the central axis.

If the average irradiation density is higher than 50 kW / m ² , the sintering process has already begun in the drying zone, which may impair the sintering result.

It has proved advantageous if the sintering zone has an irradiation density higher than 50 kW / m ² along the central axis.

An irradiation density higher than 50 kW / m ² is suitable for sintering metal particles.

In a preferred embodiment of the method of the invention, the radiator module is designed for irradiating a field having an average irradiation density in the range of 30 kW / m ² to 250 kW / m ² .

The average irradiation density associated with the field affects the energy efficiency of the device. For the entire irradiation field, an irradiation density as low as possible is basically desirable. However, average irradiation densities below 30 kW / m ² are only limitedly suitable for sintering metal-containing inks. An irradiation density higher than 250 kW / m ² hinders the energy efficiency of the device.

  It has proved to be advantageous if the radiator module has a cooling element, preferably a water-cooled cooling device, and the cooling element is arranged on the opposite side of the reflector from the infrared radiator. Yes.

  Overheating of the reflector and the infrared radiator contributes to shortening the life of the device. A cooling element, in particular a water-cooled cooling device, enables effective cooling of the infrared radiator and the reflector. Furthermore, the substrates used for the production of printed electronics basically have only limited heat resistance. Thus, the cooling element avoids overheating and damage to the substrate.

EXAMPLES Hereinafter, the present invention will be described in more detail based on a plurality of examples and three drawings.

1 is a cross-sectional view of a first embodiment of an apparatus of the present invention for drying and sintering metal-containing inks. It is a three-dimensional figure of 2nd Embodiment of the apparatus of this invention. It is a figure which shows the ray tracing simulation of irradiation intensity regarding 2nd Embodiment of the apparatus of this invention of FIG.

  FIG. 1 schematically shows a first embodiment of the device of the present invention, generally designated by the reference numeral 100. Apparatus 100 is used to dry and sinter metal-containing ink on substrate 103. The apparatus 100 is particularly suitable for drying and sintering inks in printed electronics elements produced by a roll-to-roll process.

  The apparatus 100 is based on a radiator module 101 in which infrared radiators 102a, 102b for emitting light radiation 105 are disposed, a reflector 107, and a portion of the radiation 105 emitted from the radiator module 101. And a mirror 104 for reflecting to 103.

  The infrared radiators 102a and 102b are double-tube radiators designed for continuous operation. That is, these infrared radiators 102a and 102b have a cylindrical radiator tube having a longitudinal axis of the radiator tube. The infrared radiator 102a is a carbon fiber radiator having a color temperature of 1200 ° C. Each infrared radiator 102a is assigned to a drying zone and has a radiation maximum at a wavelength of about 1.9 μm. The infrared radiator 102b is a short wavelength infrared radiator having a color temperature of about 2200 ° C. Each infrared radiator 102b contributes substantially to form a sintering zone. The maximum radiation value of each infrared radiator 102b is at a wavelength of about 1.2 μm. These two types of infrared radiators 102a, 102b emit radiation with an IR-B radiation component greater than 30% of the total radiator output and an IR-C range radiation component greater than 5% of the total radiator output. Release. These two types of infrared radiators 102a, 102b further emit more than 10% of the total radiator output in the IR-A range and the visible range.

  The infrared radiators 102 are arranged in the radiator module 101 in parallel to each other and perpendicular to the transport direction 108.

  The adjacent infrared radiators 102a have a distance 111 of 55 mm from each other, and the adjacent infrared radiators 102b have a distance of 38 mm from each other. The space | interval a between the radiator lower side of the infrared radiators 102a and 102b and the base material is 60 mm. This distance a can be easily adjusted to a range of 35 mm to 185 mm by an adjusting unit (not shown).

  The radiator module 101 has a casing 106 that is bent on two sides, the casing 106 having a surface facing the infrared radiator. A reflector 107 is attached to this surface. Since the reflector 107 includes one base reflector 107 a and two side reflectors 107 b and 107 c, most of the infrared radiation emitted from the infrared radiator 102 enters the substrate 103. The reflector 107 is made of aluminum and is suitable for reflecting infrared radiation having a wavelength in the range of 800 nm to 5000 nm. In an alternative embodiment (not shown), a highly reflective coating made of aluminum, silver, gold, copper, nickel or chromium is applied to the casing.

The radiator module 101 irradiates a predetermined irradiation field on the surface of the base material 103. This irradiation field has a drying zone 109 and a sintering zone 110 arranged on the downstream side of the drying zone 109 when viewed in the conveying direction 108. The radiator module 101 is designed to irradiate an irradiation field having an average irradiation density of about 150 kW / m ² . The irradiation field has a total area of 1800 cm ^{2 and} the area of the drying zone and the area of the sintering zone are each about 750 cm ² . The average irradiation density of the drying zone 109 and the average irradiation density of the sintering zone 110 are different. Along the central axis extending in the transport direction, the average irradiation density of the drying zone 109 is 50 kW / m ² and the average irradiation density of the sintering zone 110 is 250 kW / m ² .

  The base material 103 is a plastic film made of PET having a film thickness of 0.1 mm, and this plastic film is moved in the transport direction 108 from the transport device (not shown) toward the radiator module 101. The base material 103 moves at a constant supply speed.

  Inside the casing 106, a cooling element (not shown) for cooling the reflector 107 and the infrared radiator 102 is provided. This cooling element is a water-cooled cooling device. Water-cooled cooling devices contribute to extending the life of the device, in particular the life of the radiator and the reflector membrane. In an alternative embodiment, the cooling element is a pneumatic cooling device. Since the thermal mass of the substrate 103 is small, the cooling element in this case is designed so that the substrate 103 is not cooled by the air flow exiting the radiator module 101. This can be achieved, for example, by an air cooling device for the infrared emitter 102 and the reflector 107 with a special air conduit and a lateral air outlet, or by an air reflux cooling device for the reflector 107.

  FIG. 2 schematically shows a three-dimensional view of a radiator module 200 used in the apparatus of the present invention for drying and sintering metal-containing inks.

  The radiator module 200 includes twelve infrared radiators (not shown) and a casing 201 manufactured from a plurality of plates 202, 203, and 204. The outer dimension of the radiator module 200 is 650 mm × 450 mm × 160 mm (length × width × height). Furthermore, an inner reflector 205 is provided, and this inner reflector 205 is attached to the inner surface of the radiator module casing 201. The inner reflector 205 covers the inner surfaces of the plates 203, 204, and 208. A reflector thin plate 207 is further attached to the end face. It is possible to use as much of the radiation emitted by the infrared radiators for the irradiation of the substrate by the reflector 205, in particular by the lateral reflectors deposited on the plates 203, 204 and the reflector sheet 207. It becomes possible. The inner reflector 205 is assigned to the heated range of the infrared radiator. The unheated end of the infrared radiator protrudes from the area of the reflector 205. The radiator module 200 is designed to irradiate a field having dimensions of 600 mm × 350 mm (length × width). The lower side of the infrared radiator has a spacing h of 50 mm with respect to the substrate.

  The infrared emitter is selected and disposed within the radiator module 200 such that the irradiation profile on the irradiation field formed by the radiator module 200 includes a drying zone and a sintering zone. The unheated end of the infrared emitter is fixed to the plate 202 so that the position of the infrared emitter can be adjusted in the longitudinal direction L and thus a plurality of different irradiation profiles of the irradiation field can be set. ing.

  Arranged inside each plate 202, 203, 204 of the casing 201 is one cooling element in the form of a water-cooled cooling device 206 for cooling the inner reflector 205 and the infrared radiator.

  The plates 202, 203, 204 with cooling elements can be manufactured in various ways. For example, it can be manufactured by welding or brazing a meander-shaped U-groove on a flat substrate, or it can be manufactured by welding or brazing a half pipe on a flat substrate. Alternatively, it can be manufactured by milling a channel in the substrate and then pressing a copper tube into the channel.

FIG. 3 shows the ray tracing simulation of the irradiation intensity of the second embodiment of the apparatus of the present invention. In the diagram 300, the infrared irradiation density in the irradiation field having a dimension of 300 mm × 600 mm on the surface of the substrate made of PET film is shown in units of W / mm ² . The direction of transport of the PET film to the radiator module of the apparatus is indicated by arrows 305 in FIG.

  This ray-tracing simulation is based on the radiator module 200, ie a radiator module 200 characterized by an irradiation width B of 350 mm, an irradiation length L of 600 mm and a height H of 50.5 mm.

  The radiator module 200 is equipped with eight double-tube infrared irradiators, four of which have an output of 2 × 2.725 W (sintering zone) and the other four Has an output of 2 × 1200 W (drying zone), each with only one channel activated. Adjacent infrared emitters in the drying zone are spaced 70 mm from each other, and adjacent infrared emitters in the sintering zone are spaced 45 mm from each other.

  The distance between the PET surface and the lower side of the radiator is 50 mm. On the surface of the radiator module 200 facing the PET film, a reflector in the form of a gold film is attached.

  On the horizontal axis 301 of the diagram 300, the size of the irradiation field in the x direction is shown in units of mm, and the vertical axis 302 shows the size of the irradiation field in the y direction. The diagram 300 shows the distribution of irradiation intensity in the irradiation field in grayscale representation.

  The irradiation field is divided into four partial surfaces of the same size by a central axis 304 extending in the transport direction 305 and a vertical axis 303 extending perpendicular to the central axis 304.

This ray tracing simulation shows one irradiation field including two irradiation zones: a drying zone 307 and a sintering zone 309. The drying zone 307 has an average irradiation density of about 50 kW / m ² along the central axis 304. In the sintering zone 309, the irradiation density along the central axis 304 is 135 kW / m ² .

Furthermore, the diagram 310 shows the change in irradiation intensity in the direction of the vertical axis 303 in units of W / mm ² . A diagram 311 shows the transition of irradiation intensity along the central axis 304.

Example A metal-containing ink is printed on a plastic film made of polyethylene naphthalate (PEN) having a thickness of 100 μm by using an ink jet printer (Dimatix DMP283; droplet interval 25/30 μm). As the ink, a dispersion liquid in which silver nanoparticles (20% by weight) are dispersed in an organic solvent is used (Suntronic (registered trademark) Jet Silver U5603).

The printed plastic film is then dried by an apparatus comprising a radiator module with 2 × 2 short wavelength infrared radiators with cylindrical radiator tubes. The heated length of the radiator tube is 150 mm. A gold reflector is deposited on the side of the radiator tube opposite the coating. Infrared emitters have a broad wavelength spectrum and a color temperature of less than 2500 ° C. Infrared radiators are designed for 4 x 0.7 kW power. The output per unit area of the radiator module is 50 kW / m ² . The distance between the radiator and the film is about 50 mm. On the back side of the film, a Ceraboard radiation converter is arranged. The distance between the radiation converter and the back side of the film is about 120 mm.

  The film is moved in the transport direction to the radiator module at a tape speed of 4 cm / sec to dry and sinter the ink coating. The treatment time is 10 seconds (reference: treatment time with hot air (140 ° C.) is 40 seconds).

  The sintered coating has good conductivity and its resistance is 3Ω.

Claims (10)

An apparatus for drying and sintering a metal-containing ink on a substrate,
A plurality of light emitters for illuminating the substrate; and a reflector for reflecting radiation to the substrate;
The radiator and the substrate are movable relative to each other in the transport direction.
In the device
The light radiator is an infrared radiator having a cylindrical radiator tube and a radiator tube longitudinal axis;
The infrared radiator emits radiation whose radiant component of IR-B radiation is at least 30% of the total radiator output and whose radiant component of IR-C radiation is at least 5% of the total radiator output;
Each of the infrared radiators is disposed in one radiator module such that the longitudinal axes of the radiator tubes of the infrared radiator are parallel to each other and extend in a direction transverse to the transport direction;
A predetermined irradiation field is irradiated on the surface of the base material so as to be divided into a drying zone and a sintering zone arranged on the downstream side of the drying zone when viewed in the transport direction,
The drying zone is exposed to an irradiation density at least 15% lower than the sintering zone along a central axis extending in the transport direction;
The apparatus further includes a mirror at a position opposite to the infrared emitter with respect to the substrate, the reflector and the mirror passing a portion of the radiation emitted from the infrared emitter to the substrate. Arranged to reflect ,
The radiator module has a cooling element;
The cooling element is disposed on the opposite side of the reflector from the infrared emitter and is configured to cool the infrared emitter and the reflector;
A device characterized by that. The plurality of infrared radiators include a first type infrared radiator having a radiation maximum in a wavelength range between 1600 nm and 3000 nm, and a second type having a radiation maximum in a wavelength range between 900 nm and 1600 nm. The apparatus according to claim 1, comprising: an infrared radiator. A plurality of the first type infrared radiators and a plurality of the second type infrared radiators are provided,
3. The apparatus according to claim 2, wherein an interval between the first type infrared radiators adjacent to each other is larger than an interval between the second type infrared radiators adjacent to each other. 4. The device according to claim 1, wherein the infrared radiator emits the radiation continuously. The infrared radiator has a broadband emission spectrum;
The device according to any one of claims 1 to 4, characterized in that the radiation spectrum has a radiation component of at least 10% of the total radiator output combined in the visible and IR-A ranges. The irradiation field has a total area ranging from 800 cm ² of 6000 cm ^2,
6. The apparatus according to claim 1, wherein the area of the drying zone and the area of the sintering zone are each at least 30% of the total area. The apparatus according to claim 1, wherein the drying zone and the sintering zone have the same area. The apparatus according to any one of claims 1 to 7, characterized in that the drying zone has an average irradiation density of less than 50 kW / m ² along the central axis. 9. A device according to any one of the preceding claims, characterized in that the sintering zone has an average irradiation density higher than 50 kW / m < ² > along the central axis. The radiator module is characterized in that it is designed for irradiating the irradiation field having an average illumination density in the range of 30 kW / m ² of 250 kW / m ^2, any one of claims 1 9 The device described.

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